Fertility in France: Total Fertility Rate, completed fertility, and age at first birth

Exploring fertility through a few key questions

Graphic: Fertility from 1901 to 2022
What is the difference between cohort fertility and the fertility rate for a particular year? What was the highest average number of children per woman observed during the 20th century?

Table 1: Total fertility rate by age
In a given year, how many children do women have, on average, and at what age? Is it true that, year on year, the average number of children has been falling for the past 30 years?

Table 2 : Mean number of children at various ages, by cohort 
How much rarer is it becoming to have children before the age of 25? Given that the replacement of a generation requires an average of 2.05 children per woman, are the cohorts approaching age 50 significantly below this threshold?

Guide to this graphic

This graph shows changes in fertility over a century using two ways of calculating the number of children born to women. Each point on the red line represents a value that summarizes the births recorded in a particular year to women aged 15 to 50 during that year. This indicator, the total fertility rate (TFR), combines the prevailing age-specific fertility rates of a group of 35 different single-year cohorts for a particular year (i.e. it is representative of a short period).

The purple line represents the fertility of each cohort of women, observed from the age of 15 to the age of 50. This indicator aggregates the births occurring during the 35 years of women’s reproductive lives to obtain the average total number of children born to this cohort (completed cohort fertility, CCF). These two indicators capture fertility over different time frames. They are the sum of fertility at every age, but calculated cross-sectionally (TFR) and longitudinally (CCF).

The graph presents trends in both of these two indicators over time, showing completed cohort fertility for the cohort born in year x at year x+m on the horizontal axis, m being the mean age at childbirth for this generation (between 26 and 30). So, the CCF for the 1885 cohort, whose average age at childbirth was 28, is positioned at the same point on the horizontal axis as the TFR for the year 1913 (1885 + 28).

These two indicators are equal if the age distribution at childbirth (also known as fertility timing, the age at which women have their children) remains consistent over time. In periods when the average age at childbirth is brought forward to younger ages, the total fertility rate is higher than completed cohort fertility (the mean number of children is over-estimated). Conversely, if childbearing is postponed to later ages, the total fertility rate will automatically fall below completed cohort fertility (under-estimation of mean number of children), even if cohort fertility remains stable. Both indicators are expressed in mean number of children per 100 women.

Deciphering a century of fertility: from life trajectories to historical disruption

Fertility over the past one hundred years has not simply sustained a steady downward trend. On the contrary, we see alternating ‘highs and lows’, these oscillations being particularly marked in relation to the TFR, which fluctuates significantly from one year to the next. Fluctuations in CCF are less pronounced and this indicator has remained at between 2.0 and 2.6 children per woman throughout the past century.

The TFR was strongly impacted by the two world wars, which derailed many people’s family plans. It fell by half during World War I (from 2.3 to 1.2 children per woman between 1913 and 1916). During World War II, the decline was less dramatic since fewer men were mobilized than in 1914, but the immediate postwar rebound (‘baby boom’) was spectacular: the indicator leaps from 1.8 to 3 children per woman between 1941 and 1946–1949.

However, wars do not impact the life trajectories of everyone equally. The effects depend on the particular stage of the life course at which individuals find themselves when such historic events occur. The CCF of the cohorts born around 1880 was only slightly affected by World War I, whereas those born in the late 19th century were impacted by both wars (the 1885–1895 cohorts were aged between 25 and 44 when these two conflicts began). This partly explains the rapid decline in fertility between the 1885 cohort (2.25 children per woman) and the 1895 cohort (2.0). The world wars also produced a numerical imbalance between women and men of marital age, resulting in an increase in the numbers of single woman and, consequently, a greater decline in female fertility than in male fertility. The following generations, born after 1920, also experienced World War II as adults but only at younger ages, meaning a catch-up in postponed births was possible once peace was restored.

Fertility during the Trente Glorieuses postwar period

This resulted in the ‘baby boom’, which, in contrast to wartime, marked a phase of high fertility among men and women of reproductive age between 1950 and 1974. Completed cohort fertility among individuals born in the late 1920s climbed once again, returning to the level seen in the 1875 cohort at 2.6 children per woman.

Since the mid-1970s, the TFR has stabilized at a lower rate than CCF due to the increase in mean age at childbirth enabled by better birth control (access to modern contraception and the legalization of abortion). Previously (aside from during the wars), the TFR was higher than CCF due to the mean age at childbirth becoming younger. From 1920 to 1930, a scissor effect can be seen: CCF increases while the TFR decreases. The latter decline is produced because the sharp increase in births seen at the end of the 1914–1918 war is not sustained, leading to falls in total fertility soon after. Fertility is low in the interwar period, as it was throughout the 19th century, with French couples being particularly Malthusian.

Recent trends and projections for the future

Women born in the mid-1970s and having reached the age of 50 have, on average, 2.02 children. The completed fertility of women born in 1985 is easy to estimate since very few births take place after the age of 40 (they have already had 1.95). If we assume that, over the next ten years, they have the same fertility at ages 40–49 as women of this age group in 2020, their completed fertility will be 2.05 children. Overall, therefore, the fertility of the 1960–1987 cohorts has remained relatively stable (between 2.0 and 2.1).

How will the cohorts born after 1985 behave over the next ten years? Young people of under 30 years of age, irrespective of their social group, want fewer children: the total number of children that women wish to have has fallen by 0.6 children on average over the past twenty years (from 2.5 to 1.9 children between 2005 and 2024 (Bouchet-Vallat and Toulemon 2025). A projection of various scenarios for changes in age-specific fertility predicts a fall in completed cohort fertility in all scenarios. For the 1995 cohort, completed fertility could be between 1.60 and 1.94 children, below the replacement level (2.06).